Leakdown Testing - Page 2

Mike Taylor 3601 · 10-04-2012, 08:28 AM

Mine is supposed to be connected and then adjusted to 100psi then backed down to 60 psi before disconnected so then when connected to next cylinder it starts @ 60 psi
Mike Taylor 3601

Marine One · 10-04-2012, 08:36 AM

There are a lot of ways to check "in cylinder performance". I have experimented with hot engines, cold engines, dry cylinders, wet cylinders, compressed air, compressed nitrogen, various grades of oil, etc. I have even gone as far as recording how much vaccum a cylinder pulls to understand how the rings seal to the tops of the ring grooves on the way down during the intake stroke. Much harder to get rings to seal while pulling vacuum.

Regardless of your method, you need to check frequently and you need to check consistently. Since you are trying to predict wear, you need to have a good benchmark of what is good before you can say what is bad. Get a baseline reading at rebuild and make it a point to check all cylinders again, the same way you established your baseline. Then measure and record everything the exact same way after you have burnt so many gallons of fuel. Example - at every 50 gallons of fuel burnt, measure, record and look for a trend.

FED 387 · 10-04-2012, 12:05 PM

usually somewhere either on the gauge or in the instructions it will give you a range of air pressure needed so that the gauge will function properly----my particular gauge is a Sun it ranges from 70-200 pounds needed----turn the engine to a position where BOTH rocker arms have NO tension on them so that the neither of the valves are open at all-- then go do your test---we pump air into the cylinder , disconnect the air line to that cylinder then re- attach the air hose and take the reading--works for us just remember to do your routine the EXACT same way every time--- hot ,cold, medium temp engine odd numbers first whatever how ever it works best for you

BlueOval Ralph · 10-04-2012, 01:50 PM

Those Sun Leak Down testers are like Gold I have two one in the shop and the one in the trailer. When there is a auction in the area I look for them. As I remember no mater what the input pressure is the only put 30 or 60 psi into cylinder.

motohead1 · 10-04-2012, 02:07 PM

Thanks to everyone for all the info. Chuck

Ed Wright · 10-04-2012, 02:49 PM

Quote:

Originally Posted by BlueOval Ralph

Those Sun Leak Down testers are like Gold I have two one in the shop and the one in the trailer. When there is a auction in the area I look for them. As I remember no mater what the input pressure is the only put 30 or 60 psi into cylinder.

That's what I use. Have had mine for forty years. (got it in 1972) Still works like new. Just needed a new hose once.

FED 387 · 10-04-2012, 03:17 PM

Yep had mine bout that long too-NO its not for sale---one more thing remember to RESET TO ZERO the % gauge before you go do the next cylinder( part of the attach/ unattach/attach tap the lense LIGHTLY routine---REPEATABILITY is what counts here---this is not rocket science merely comparing one cylinder to another looking/hearing for wear or malfunctions/damage---we always leak a new engine before start up/after initial start up to get a baseline for the future to see how much wear we really are getting as we put runs on the car--but we do leak it at the end of EVERY day racing just to see whats going on-FED387

Harry 6674 · 10-04-2012, 03:41 PM

It's also good to check for leaks with the piston all the way down (with rockers backed off). Just a little more information.

David Lee · 10-05-2012, 04:05 PM

Good day, can a leak down test be done on a cold engine?

Ed Wright · 10-05-2012, 04:41 PM

Quote:

Originally Posted by David Lee

Good day, can a leak down test be done on a cold engine?

Sure.

10-04-2012, 08:28 AM	#11
Mike Taylor 3601 VIP Member Join Date: Oct 2008 Location: Somerset,Ky Posts: 1,372 Likes: 354 Liked 307 Times in 103 Posts	Re: Leakdown Testing Mine is supposed to be connected and then adjusted to 100psi then backed down to 60 psi before disconnected so then when connected to next cylinder it starts @ 60 psi Mike Taylor 3601

10-04-2012, 08:36 AM	#12
Marine One Junior Member Join Date: Mar 2010 Location: Indiana Posts: 69 Likes: 2 Liked 0 Times in 0 Posts	Re: Leakdown Testing There are a lot of ways to check "in cylinder performance". I have experimented with hot engines, cold engines, dry cylinders, wet cylinders, compressed air, compressed nitrogen, various grades of oil, etc. I have even gone as far as recording how much vaccum a cylinder pulls to understand how the rings seal to the tops of the ring grooves on the way down during the intake stroke. Much harder to get rings to seal while pulling vacuum. Regardless of your method, you need to check frequently and you need to check consistently. Since you are trying to predict wear, you need to have a good benchmark of what is good before you can say what is bad. Get a baseline reading at rebuild and make it a point to check all cylinders again, the same way you established your baseline. Then measure and record everything the exact same way after you have burnt so many gallons of fuel. Example - at every 50 gallons of fuel burnt, measure, record and look for a trend. __________________ Chad Sheets \| STK 319 \| 10.69 \| 1.39 Last edited by Marine One; 10-04-2012 at 08:38 AM.

10-04-2012, 12:05 PM	#13
FED 387 VIP Member Join Date: Jun 2006 Posts: 3,420 Likes: 529 Liked 333 Times in 180 Posts	Re: Leakdown Testing usually somewhere either on the gauge or in the instructions it will give you a range of air pressure needed so that the gauge will function properly----my particular gauge is a Sun it ranges from 70-200 pounds needed----turn the engine to a position where BOTH rocker arms have NO tension on them so that the neither of the valves are open at all-- then go do your test---we pump air into the cylinder , disconnect the air line to that cylinder then re- attach the air hose and take the reading--works for us just remember to do your routine the EXACT same way every time--- hot ,cold, medium temp engine odd numbers first whatever how ever it works best for you

10-04-2012, 01:50 PM	#14
BlueOval Ralph Banned Join Date: Feb 2008 Posts: 852 Likes: 0 Liked 0 Times in 0 Posts	Re: Leakdown Testing Those Sun Leak Down testers are like Gold I have two one in the shop and the one in the trailer. When there is a auction in the area I look for them. As I remember no mater what the input pressure is the only put 30 or 60 psi into cylinder.

10-04-2012, 02:07 PM	#15
motohead1 Junior Member Join Date: Apr 2009 Posts: 8 Likes: 0 Liked 0 Times in 0 Posts	Re: Leakdown Testing Thanks to everyone for all the info. Chuck

10-04-2012, 03:17 PM	#17
FED 387 VIP Member Join Date: Jun 2006 Posts: 3,420 Likes: 529 Liked 333 Times in 180 Posts	Re: Leakdown Testing Yep had mine bout that long too-NO its not for sale---one more thing remember to RESET TO ZERO the % gauge before you go do the next cylinder( part of the attach/ unattach/attach tap the lense LIGHTLY routine---REPEATABILITY is what counts here---this is not rocket science merely comparing one cylinder to another looking/hearing for wear or malfunctions/damage---we always leak a new engine before start up/after initial start up to get a baseline for the future to see how much wear we really are getting as we put runs on the car--but we do leak it at the end of EVERY day racing just to see whats going on-FED387

10-04-2012, 03:41 PM	#18
Harry 6674 Senior Member Join Date: Dec 2006 Posts: 589 Likes: 0 Liked 0 Times in 0 Posts	Re: Leakdown Testing It's also good to check for leaks with the piston all the way down (with rockers backed off). Just a little more information.

10-05-2012, 04:05 PM	#19
David Lee VIP Member Join Date: Oct 2007 Posts: 1,168 Likes: 487 Liked 346 Times in 126 Posts	Re: Leakdown Testing Good day, can a leak down test be done on a cold engine?